Back to the ROSAT and ASCA era, [1]} reported from a sample of four galaxy groups that SNcc products (i.e. Si and Mg) were found to be more uniformly spread, while SNIa products (namely, Fe) showed a more peaked distribution. These results were naturally interpreted as the bulk of SNcc having exploded, gotten mixed with, and enriched their surroundings earlier than the bulk of SNIa (the latter being more likely to originate from long-lived low-mass star populations in the red-and-dead central dominant galaxy). That interpretation was later supported by [2]}, [3]} who measured a radial increase of the Si/Fe ratio with Chandra observations of 15 groups.
